Various types of air purification system are known in the art. For example, dust filtering screens and/or dust collecting bags are widely used in traditional air purification systems, in which the dust particles are arrested on the dust filtering screens or in the dust collecting bags. This air purification method has an advantage of simplicity; however, it requires cleaning or replacing the dust filtering screens or the dust collecting bags on regular basis, and thus is very inconvenient and also uneconomical. In the meantime, the existence of dust filtering screens or dust collecting bags will also create a relatively high air resistance. This air resistance will block the air flow motion, and therefore lower the efficiency of dust particulate removal.
U.S. Pat. No. 7,594,954 discloses an air purification system which can collect dust particulates from air flow by means of electrostatic effect. To this end, this air purification system includes an electrostatic filter, which is provided with several electrodes, including a discharge electrode and a passive electrode being connected to high-potential and low-potential terminals of high voltage power supply respectively. Although achieving a more or less satisfactory dust particulate efficiency, the electrostatic filter requires a high voltage power supply to generate electrostatic effect, which not only increases the operation cost but also complicates the structure of the system.